我如何为测试目的修改方法的行为?

Question

# file: cisco_driver.py
class myClass:
def __init__(self, run_commands):
self.run_commands = run_commands
def myFunction(self, interface_name):
command = f"show interface status {interface_name}"
output = self.run_commands(command)
return output

1. 函数myFunction以接口名作为输入，例如:myFunction("Gig1/1/1")
2. 然后生成一个命令，在本例中为:show interface status Gig1/1/1
3. 然后使用run_commandsSSH到设备，执行命令，并检索其输出

为了进行pytest测试，我想测试生成的命令，且不该命令的执行。我想绕过run_commands并返回命令本身，而不是它的输出。

我怎样才能做到这一点?这可能吗?我能嘲笑一下吗?Monkeypatch吗?

我想让它像这样运行:

def myFunction(interface_name):
command = f"show interface status {interface_name}"
return command

Answer 1

我玩了一下，找到了一个解决方案:

# pytest_file
def test_case():
# Initialize new instance of class
# Use None since "run_commands" will be bypassed
new_instance = myClass(None)
# New function that will replace the existing run_commands function
def mock_run_commands(command)
# Original behavior of run_commands is to create an SSH connection
# Instead, I want it to return the same command
return command
# Redefine run_commands to my customized function
new_instance.run_commands = mock_run_commands
# Pass param through class method
# This will return "show interface status Gig1/1/1"
selected_command = new_instance.myFunction("Gig1/1/1")
# Compare the command produced by class method with what expected outcome
assert selected_command == expected_command